I have a Scott 233 amp that over the summer I want to collect up the best (I can afford) Tubes, Caps and other various little parts needed to do a complete upgrade on the amp. it is currently working and sounding good. So I don't need to find any problems hopefully just make it better.

Since I can collect a bunch of stuff due to limited room (and I just can't justify buying up stuff I won't be using) I figure that I can afford to do a few units to the best of my ability.

To this end I would like recomendations for what brand/versions of the Tubes this amp will need.

(4) 12AX7
(2) 6U8
(4) 7591 outputs
(1) 5AR4 rectifier

is there a certain brand that makes a better quality one of these tubes. I already know about matched pairs or better yet matched quads. But I see a number of new tubes NOS tubes and used tubes said to test like new. And then of course a number of brands.


I got this amp in very nice cosmetic condition and for what I know to be a very good price. So I figure if I make an investment in getting into the best condition I can I can only be happier with it and I will learn a lot about it along the way.

I wouldn't mind recomendations for good dealers to buy from either.

thanks

for the 12ax7s... the Brimar/Mullard CV4004s RCA Black Plates, Telefunkens.

The Mullard 12AX7's are truely magical in my Fisher amps. For 7591 I like Sylvania but have heard good things about some current production. IMHO if I have a certain budget I spend more on the front end tubes. I can here more difference when tube rolling the front. Just remembered another excellent 12AX7, Matsushita, a little hard to find but very bright and clear, esp. good fo r female voice! I guess what I'm saying is, if I was going to do a complete retube say on my Fisher 200, I would buy current prod. 7591's, and try to find NOS Mullard, Tele, Matsushita, Amperex, etc. for the 12a's. Good Luck, Jay

Like Jay I think current production 7591's are the way to go.

I haven't heard much of a difference in the rectifiers or the 6u8 so as long as you've
got some working ones that are in good shape that's about the extent I would go for.

Now the 12ax7's you get all the different oppinions you want till the cows come home.
The only new production ones I've tried that sounded good were EI's. I think NOS Rca
are a very underated tube and the Tellies are overated (unless in the right circuit). My
favorite is Bugle Boys then any of the other Amperex ones, Mullards in the right place
can be just magic but in the wrong situation can be dark and rob the livelyness a unit
could otherwise posess with say maybe an Rca cleartop or even the Tellies if the piece
needs waking up.

So there really is no "best tube" it's system/piece/taste determined. Now someone who
works on your particular gear may be able give you a more precise recomendation with
knowing the gear and if they've done some rolling.

My suggestion is jump on Ebay and throw some cheap bids at some known 12AX7's to
see what the tide brings in and if you need some 6U8's or a 5AR4 do the same.

Well I trying to lear fast and I think what I am hearing so far is telling me that picking out the best tubes might be best left until after the caps are replaced along with any other improvements to the circuits in the amp. Other wise I might be picking a tube that doesn't sound as good as it could since I changed something else.

I have been offered a 12AX7 lending library to try out so I think I will get the other upgrades done first and then do some testing before I purchase.

All fun stuff.

You will get a hundred fold more improvement in the sound of your amplifier by rebuilding it with quality parts! Do that first then start tube rolling like you mentioned.

The best of the best IMHO (for the Scott that is, there is no best of any given tube type)

12AX7's Telefunken, Telefunken, Telefunken

6U8A Telefunken, Telefunken, Telefunken very hard to find most USA made are great also RCA and Sylvania are some nice choices the key with this tube is to find quiet ones I buy them by the sleeves 30 to 50 at a times and regularly toss 1/2 of them out. DO NOT BUY USED 6U8's

7591 Any NOS original type but the JJ new production work darn fine. The NOS are hard to source and usually near the end of there life in used condition.

5AR4 Mulllard or Amperex but a modern Sovtek will work wonderful.

I have found through years of rebuilding vintage gear that is almost all cases what the amp was specified and designed with is usually the best tonal balance. Scott was a huge user of Telefunken small signal tubes hence my recomendations.

*keep in mind the tube rolling is in most cases very subtle change. A Personal preference based hobby it can however fun as hell if your a serious listener. So keep in mind what I like you could easily hate. What Kegger likes you could love or hate. It's best to do your tube rolling after the amp has been rebuilt and burned in unless of course it needs tubes now*

"Well I trying to lear fast and I think what I am hearing so far is telling me that picking out the best tubes might be best left until after the caps are replaced along with any other improvements to the circuits in the amp. Other wise I might be picking a tube that doesn't sound as good as it could since I changed something else".


Mark--exactly right. A case in point: I was rolling tubes in my Jolida cd player while my Kenwood 600 was being recapped. I was using in its place my non-recapped 500, which had roughly the same sonic qualities as the 600. Anyway, when the recapped 600 came back, everything had changed--the bass was much fuller, and the mids and highs were brighter and cleaner. Fortunately I still had a range of tubes to try out and ended up making entirely different selections.

I have a 233 also and agree with Craig the telefunken 12ax7 seem to be the best to my ears. I have tried bugle boys, ei's and ampex but prefer the telefunken.

So far this is what I know about 12ax7s.

Mullards/Blacktop RCA: Great on amps that are a bit too bright
Telefunkens: Great on amps that are a bit too dark

These are expensive sure, but you did want to know what the best was; if you're willing to pay top dollar I hope you know what your amp needs to improve on so you don't end up wasting your money.

Thanks Craig and other guys I am making up a little note sheet of the advise I'm getting so I don't forget any of this this winter when I sit down to start serious work on this amp.

I will how ever keep my eyes open for deals on some of the recomemded tubes just in case something good comes along.

As always I greatly appreciate any help.

IMHO I would go with the Groove Tube 12AX7M. For the caps I would recommend Solen Fast.

I have a scott 299b the one it works very well with the philips EL84, RCA 6BL8, RCA 12AX7 and an amperex 5AR4. I have understood that the queen of the valves is the telefunken, some day I will have it, good luck, Martin
Hi, I didn't get telefunken but I got some siemens E84L, similar at 7189, very but very good, vacuum tubes, Martin

mark,

the tubes i'll be sending in the heathkit will be great for rolling in the scott as far as the 12ax7's go.there'll be 5 matched 12ax7's all from the same mfg .thats all im saying for now. :D

Chris You crack me up.

I think well do something on that little heathkit next week I look to be working a full week so the fun money should be available.

I think well do something on that little heathkit next week I look to be working a full week so the fun money should be available


sounds like a plan mark. :yes:

As far as the 5AR4 tube is concerned, I second the recommendation for MULLARD.They are superb, far better than any other brand I tried.But these days they fetch big bucks on ebay, IMO worth the cost.

Chris